You might want to rethink that cola and hamburger as these foods may be shrinking your brain. New research in the online journal BMC Medicine found that the Standard American Diet (SAD) can cause shrinkage of a part of the brain known as the left hippocampus. While poor dietary choices have been linked to many health concerns, including: heart disease, cancer, diabetes, and others, this study is the first human study to link poor diet to brain shrinkage of the hippocampus.

The left hippocampus is a portion of the brain involved in memory, learning, mood regulation, and depression in particular. Since this is the first part of the brain to deteriorate in Alzheimer's disease this study is significant to our understanding of causal factors for this serious disease as well.

The study analyzed 2551 Australians between the ages of 60 and 64 at the outset of the study who participated in dietary questionnaires, cognitive, and physical health assessments. For a second round of assessments, 2222 of the original people agreed to have a second round of tests four years later, of which 622 of the original people were randomly selected to have brain MRIs at the four year mark.

The researchers found that those who ate a Western diet consisting of refined carbohydrates like sugary foods and beverages and higher amounts of saturated fats which are found in meats and cheeses had significantly smaller left hippocampus size than those who ate a healthier diet. An unhealthy diet was characterized by inclusion of: roasted meats, sausages, chips, hamburgers, steaks, fries, and soft drinks. The scientists described a healthier diet as one with lower intakes of refined carbohydrates and saturated fats, with higher intakes of nutrient-dense foods like vegetables, fruits, whole grains, green salads, and fish.

This is a ground-breaking study because, while it has been established for years that the hippocampus is typically the first part of the brain to deteriorate in Alzheimer’s patients, it has not been studied in humans to see if there is a correlation to dietary factors. In earlier studies, brain diseases like depression have been linked to stress, low-grade inflammation, free radical damage, and imbalanced gut microbes, all of which are still considered important factors to address in brain disease prevention and treatment. This new study demonstrates that diet can influence the actual size of the hippocampus, which when shrunk is further linked to brain diseases like depression and Alzheimer’s.

The long-held medical belief that diet can't do much to influence the health of our brain or prevent brain diseases is now outdated and irrelevant. Study after study shows that brain health is significantly impacted by your food choices, for better or worse. Perhaps fast food and junk food manufacturers should add “may cause brain shrinkage” to the labels of their products? That cola and hamburger are certainly sounding a lot less appetizing aren’t they?